Anomalies are ranked in difficulty by 10 levels, these are:

1* (Faction) Burrow / Drone Collection (lowest)
2* (Faction) Hideaway / Drone Cluster
3* (Faction) Refuge / Drone Gathering
4* (Faction) Den / Drone Gathering
5* (Faction) Yard / Drone Surveillance
6* (Faction) Rally Point / Drone Menagerie
7* (Faction) Port / Drone Herd
8* (Faction) Hub / Drone Squad
9* (Faction) Haven / Drone Patrol
10* (Faction) Sanctum / Drone Horde (hardest)